SmogRank / History / Country race
Countries, worst air first, day by day
Each country's typical measured city over the 30 days to every day since January 2023, worst first. Press Play to watch the order change, or drag the slider to any day.
The worst countries for PM2.5 over the 7 days to 22 Sep 2023: Pakistan 41.4 µg/m³, Peru 26.3 µg/m³ and China 23.9 µg/m³.
- 1Pakistan3 cities41.4
- 2Peru4 cities26.3
- 3China3 cities23.9
- 4Chile44 cities23.0
- 5India5 cities17.8
- 6Thailand10 cities14.8
- 7Greece7 cities14.0
- 8Mexico40 cities13.7
- 9Malta4 cities13.6
- 10Serbia3 cities13.4
- 11Singapore5 cities10.9
- 12Bulgaria6 cities10.8
- 13Poland55 cities10.8
- 14Italy29 cities10.6
- 15Hungary9 cities10.5
- 16Czechia36 cities9.6
- 17Hong Kong12 cities8.8
- 18Japan548 cities8.7
- 19Slovakia27 cities8.6
- 20Romania6 cities8.4
+ 16 more countries, 8.0 µg/m³ and below
- 21United States758 cities8.0
Not counted on this day, too few cities measured: North Macedonia since 16 Sep 2023, Lithuania since 11 Sep 2023 and Luxembourg since 6 Sep 2023.
Countries counted each day
A country's number is its typical measured city: the median of its cities' means over the 30 days (a city needs 21 of them measured; 5 of 7 on the 7-day race), shown only with 3 such cities. A country whose monitors go quiet fades out where it stood rather than sliding down, so a gap never reads as cleaner air; "was" beside a city count marks a month after many cities joined or left. Some large countries are thin or missing because their monitors' licences don't allow reuse. How we rank.
Not covered: the government monitoring networks of China and Turkey, which publish only on their own websites; we are building the readers for them. Most cities there are missing from this board, not clean. Why.